Retaining wall and construction method therefor

ABSTRACT

An object of the invention is to provide a retaining wall and a construction method therefor whereby fixation between a steel sheet pile wall and a formwork panel to form the retaining wall is made easy, and can be reliably made, so that construction schedule reduction is achieved. The retaining wall is composed of steel sheet piles  100  driven in the ground preliminarily, a formwork panel  201  fixed in close contact with a face of the steel sheet piles  100  opposite to a ground region, and a formwork panel  202  vertically provided at a position facing the formwork panel  201 . The formwork panels  201  and  202  are vertically provided on runners  204  fixed preliminarily to the ground by screws  203 , and have caps  205  on their tops to maintain horizontal states and linear states of the formwork panels  201  and  202.

TECHNICAL FIELD

The present invention relates to a retaining wall and a construction method therefor, and in particular to a retaining wall and a construction method therefor that facilitate connection and fixation between steel sheet piles preliminarily driven and a formwork panel arranged parallel to the steel sheet piles.

BACKGROUND ART

In an open-cut work for constructing an underground structure such as a building foundation, which is conventionally performed, after a retaining wall is provided and excavation and removal within the wall are performed, an outer formwork for casting concrete is provided via an about 80-90 cm wide trench from the retaining wall, and further an inner formwork is provided inside the outer formwork. This trench is intended to secure a workspace when setting up the inner formwork and removing the same after hardening the concrete.

On the other hand, in order to provide the trench, it is necessary to perform extra open-cut beyond an open-cut width required for construction of an underground structure. For this reason, not only it is extremely difficult to perform open-cut work in a narrow site, but also there is a problem such as the need of extra construction hours and construction costs. Therefore, such open-cut work has the problem of reducing construction schedule.

In this regard, there is a construction method to avoid trench to be subjected to open-cut, thereby achieving open-cut scale reduction and construction schedule reduction obtained by reducing the open-cut width (Patent Document 1). This construction method described in the patent document 1 is such that a water-tight non-corrosive panel doubling as the outer formwork is vertically provided abutting on or in the vicinity of retaining piles, the inner formwork is provided inside the panel, concrete is cast, the cast concrete and the panel are integrally left behind in the ground, and then the retaining piles are pulled out.

This construction method can facilitate pulling out the retaining piles through the use of the panel with a low coefficient of friction, and can also reduce the width of open-cut excavation, thereby achieving construction schedule reduction and cost reduction.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: Japanese Patent No. 2969607

SUMMARY OF THE INVENTION Problem to be Solved by the Invention

By the way, in the above construction method, the panel is bonded to the retaining piles with an adhesive agent or a double-stick tape, but the work of bonding the panel to the retaining piles requires a lot of time and a large number of workers regardless of the open-cut scale, which makes construction cost reduction difficult.

The present invention has been made in view of these circumstances, and an object thereof is to provide a retaining wall and a construction method therefor which facilitate fixation of a steel sheet pile wall serving as the retaining wall and the formwork panel to each other and make it possible to ensure the fixation, and which achieve construction schedule reduction.

Means for Solving the Problem

In order to achieve the above object, a retaining wall of the present invention is a retaining wall constructed by preliminarily driving steel sheet piles sequentially to construct a steel sheet pile wall forming continuous corrugation and performing excavation on one side of the steel sheet pile wall, the retaining wall including a first formwork panel arranged parallel to the steel sheet pile wall in a direction parallel to and in close contact with the one side of the steel sheet pile wall; and a second formwork panel arranged parallel to the steel sheet pile wall at a position corresponding to the width of a base structure to be constructed.

Further, in the retaining wall of the present invention, the formwork panel is fixed to the closely-contacting steel sheet piles by a fixing member.

Further, a construction method for a retaining wall of the present invention includes a step of preliminarily driving steel sheet piles sequentially to construct a continuously-corrugated steel sheet pile wall in a plot of land where the retaining wall is constructed; a step of performing excavation on one side of the steel sheet pile wall; a step of arranging a first formwork panel parallel to the steel sheet pile wall and in close contact with the one side of the steel sheet pile wall; a step of arranging a second formwork parallel to the steel sheet pile wall at a position corresponding to the width of a base structure to be constructed; a step of casting concrete to construct the base structure; a step of performing backfill by feeding soil into recessed portions of the steel sheet pile wall; and a step of pulling out the steel sheet pile wall.

Advantageous Effect of the Invention

According to the present invention, since the formwork panel can be easily arranged parallel to and in close contact with the steel sheet pile wall driven, and the formwork panel doubles as an outer formwork, extra open-cut is not required, and a construction plot of land can be sufficiently utilized, so that it becomes possible to reduce the construction schedule.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view showing a vertical section of a retaining wall according to the present embodiment;

FIG. 2 is a view showing a configuration of a formwork panel used in constructing the retaining wall;

FIG. 3 is a view showing an A-A cross section of the formwork panel shown in FIG. 2;

FIG. 4A is an enlarged view showing a connection region between steel sheet piles and the formwork panel, and FIG. 4B is a vertical sectional view showing the connection state between the steel sheet piles and the formwork panel;

FIG. 5 is a flowchart showing a construction procedure for the retaining wall according to the present embodiment;

FIG. 6A is a view showing a state that the steel sheet piles are driven into the ground, and FIG. 6B is a view showing a state that a predetermined plot of land is excavated;

FIG. 7A is a view showing a state that the formwork panel is provided on the steel sheet pile wall, and FIG. 7B is a view showing a state that an opposing formwork panel is provided; and

FIG. 8A is a view showing a state that concrete is cast and backfill is performed, and FIG. 8B is a view showing a state that the steel sheet piles are pulled out.

BEST MODE FOR CARRYING OUT THE INVENTION

Next, a construction method for a retaining wall according to the present embodiment will be described with reference to the drawings.

FIG. 1 is a view showing a vertical section of the retaining wall according to the present embodiment.

As shown in FIG. 1, the retaining wall is composed of steel sheet piles 100 driven in the ground preliminarily, a formwork panel 201 fixed in close contact with a face of the steel sheet piles 100 opposite to a ground region, and a formwork panel 202 vertically provided at a position facing the formwork panel 201. The formwork panels 201 and 202 are vertically provided on runners 204 fixed to the ground preliminarily by screws 203, and provided with caps 205 on their tops to maintain horizontal states and linear states of the formwork panels 201 and 202. Further, a plurality of pipes 206 are fixed horizontally to one face of the formwork panel 202, and supports 300 for supporting the formwork panel 202 against a lateral pressure when casting concrete is further provided.

Reinforcing bars are disposed and concrete is cast in a space between the formwork panels 201 and 202 thus vertically provided, so that a concrete structure can be constructed. It should be noted that, after the concrete structure is constructed, the supports 300 are removed, a space in which the steel sheet piles 100 are driven is backfilled, and the steel sheet piles 100 are pulled out vertically.

Next, the configurations of the formwork panels 201 and 202 used in constructing the retaining wall of the present embodiment will be described.

As shown in FIGS. 2 and 3, each of the formwork panels 201 and 202 is a left-in-concrete type formwork panel formed by bending a steel plate-like material into a substantially quadrangular shape in plan view and a substantially angular-wave like shape in cross section, and cutting the same. In each of the formwork panels 201 and 202, a plurality of parallel ridges 11 are arranged at predetermined intervals by bending the panel steel plate into a substantially angular-wave like shape in cross section, so that the strength of the panel itself is reinforced. Further, by forming the panel in an equilateral wave like shape in its cross section, the panel can exert its excellent strength especially against force from its surface or rear face.

It should be noted that, in the present embodiment, a direction in which the ridge 11 is formed is defined as a longitudinal direction of each of the formwork panels 201 and 202, and a direction perpendicular to the longitudinal direction is defined as a lateral direction of each of the formwork panels 201 and 202.

As shown in FIGS. 2 and 3, the ridge 11 is composed of a top face 31, and two side faces 32 provided to connect to the top face 31 in both lateral directions thereof. Further, in each recessed face between the ridges 11, a plurality of ribs 12 raised in their lateral cross section and grooves 16 recessed in their lateral cross section are alternately and repeatedly formed parallel to the ridges 11.

Further, in both ends of the ridge 11 in the panel lateral direction thereof, that is, on boundary lines between the ribs 12 and the grooves 16 adjacent to the ribs 12, slits 13 each having a predetermined length are made parallel to the ridge 11 at predetermined intervals like a broken line. By bending each of the formwork panels 201 and 202 at a predetermined angle along this row of broken-line-like slits 13, a corner portion of a formwork can be formed. Further, by bending each of the formwork panels 201 and 202 along this row of broken-line-like slits 13 forward and backward alternately and repeatedly, each of the formwork panels 201 and 202 can easily be cut into a desired size.

Further, the slit 13 is a slit having a very narrow width and a predetermined length and penetrating each of the formwork panels 201 and 202, and the width of the slit 13 is formed so as to be capable of discharging liquid concrete or excess water from the slit 13 after backfill of soil and casting of concrete.

Further, on the side of the top face 31 of the ridge 11 is provided with a plurality of flap-like lids 14. By opening the lid 14, such a work as causing a member used in vertically providing each of the formwork panels 201 and 202 to penetrate the ridge 11 is made possible.

Next, a method of fixing the steel sheet piles 100 and the formwork panel 201 together will be described with reference to FIG. 4.

FIG. 4A is an enlarged view showing a connection region between the steel sheet piles and the formwork panel, and FIG. 4B is a vertical sectional view showing the connection state between the steel sheet piles and the formwork panel.

As shown in FIG. 4A, the steel sheet pile 100 used in the present embodiment is a U-shaped steel sheet pile provided with a web portion 101 and flange portions 102 integrated with the web portion so as to slope from both ends of the web portion 101, and the flange portion 102 is provided with a joint portion 103 at its distal end to join the steel sheet pile 100 with an adjacent steel sheet pile 100. These steel sheet piles 100 are alternately arranged with their joint portions 103 joined together so as to construct a continuous wall body in the ground while repeating corrugation. Then, the formwork panel 201 is arranged parallel to the steel sheet piles 100 so as to be in close contact with the web portions 101.

At this time, a space is formed between the formwork panel 201 and a recessed portion formed in the steel sheet piles 100, and a crosspiece 104 is fitted in this space. When the crosspiece 104 is fitted in the space, the flange portions 102 abut on corner portions of the crosspiece 104, thereby fixing the crosspiece 104 between the flange portions 102 in the space. Then, the crosspiece 104 and the formwork panel 201 are fixed together by a fixing runner 105. As shown in FIG. 4B, the fixing runner 105 is substantially U-shaped, and fixed to the crosspiece 104 and the cap 205 attached to an upper end of the formwork panel 201 by a screw or the like.

It should be noted that the fixation between the steel sheet piles 100 and the formwork panel 201 is not limited to the above manner, and the steel sheet piles and the formwork panel may be fixed together by a separator depending on the construction position, or they may be fixed together in any other manner. On the other hand, the steel sheet piles 100 and the formwork panel 201 are not necessarily fixed together, and, simply, the formwork panel 201 may be vertically provided in close contact with the steel sheet piles 100.

By the way, though the formwork panel 201 is in contact with the steel sheet piles 100 and fixed thereto, only the web portions 101 and the grooves 16 composing the formwork panel 201 are in close contact with the steel sheet piles 100 in the longitudinal direction. Therefore, the area of contact between the steel sheet piles 100 and the formwork panel 201 can be reduced, and the steel sheet piles 100 can also be smoothly pulled out of the ground.

Further, the crosspiece 104 and the fixing runner 105 fixing the steel sheet piles 100 and the formwork panel 201 can be easily detached, and the steel sheet piles 100 can be easily pulled out, so that construction schedule reduction can be achieved.

Next, a construction procedure for the retaining wall according to the present embodiment will be described with reference to FIGS. 5 to 8.

FIG. 5 is a flowchart showing the construction procedure for the retaining wall according to the present embodiment, FIG. 6A is a view showing a state that the steel sheet piles are driven into the ground, FIG. 6B is a view showing a state that a predetermined plot of land is excavated, FIG. 7A is a view showing a state that the formwork panel is provided on the steel sheet piles, FIG. 7B is a view showing a state that an opposing formwork panel is provided, FIG. 8A is a view showing a state that concrete is cast and backfill is performed, and FIG. 8B is a view showing a state that the steel sheet piles are pulled out.

[Driving of Steel Sheet Piles and Excavation of the Ground]

First, as shown in FIG. 6A, the steel sheet pile wall 100 is constructed by driving the steel sheet piles 100 at a position corresponding to the width of an underground structure to be constructed (Step S100). Next, as shown in FIG. 6B, the ground is excavated by heavy equipment or the like (not shown), and the excavated surface is subjected to surface compaction. At this time, soil filling the recessed portions of the steel sheet pile wall 100 repeating corrugation is removed (Step S101).

[Parallel Arrangement of Formwork Panels]

Next, as shown in FIG. 7A, the formwork panel 201 is arranged parallel to the steel sheet pile wall 100. At this time, the formwork panel 201 is vertically provided on the runner 204 fixed to the ground preliminarily by the screws 203, and the cap 205 is provided on the top of the formwork panel 201. Then, as described above, the crosspiece 104 is fitted in the recessed portion of the steel sheet pile wall 100, and the crosspiece 104 and the formwork panel 201 are fixed together by the fixing runner 105. On the other hand, as shown in FIG. 7B, the formwork panel 202 is similarly vertically provided on the runner 204 provided preliminarily so as to face the formwork panel 201 (Step S102). Then, the supports 300 for responding to lateral pressure when casting concrete are provided on the formwork panel 202.

Further, pipes (not shown) may be provided horizontally on one face of the formwork panel 202.

[Casting of Concrete and Pulling-Out of Steel Sheet Piles]

Next, as shown in FIG. 8A, reinforcing bars or the like are disposed between the formwork panel 201 and the formwork panel 202, and then concrete is cast, and the supports 300 are removed (Step S103). Then, backfill is performed by feeding soil into voids in the recessed portions of the steel sheet pile wall 100 (Step S104). Next, as shown in FIG. 8B, the steel sheet piles 100 are pulled out by heavy equipment in a conventional manner (Step S105).

As described above, the retaining wall and the construction method therefor according to the present embodiment makes it possible to easily arrange the formwork panel parallel to and in close contact with the steel sheet pile wall driven. Further, since the formwork panel doubles as an outer formwork, it is possible to utilize a construction plot of land sufficiently without performing extra open-cut, so that the construction schedule can be reduced. Further, since the formwork panel can be easily changed in size or shape, the parallel arrangement is made easy in accordance with the configuration of the steel sheet pile wall. Further, since the steel sheet pile wall has a small area of contact with the formwork panel, the coefficient of friction with the formwork panel can be reduced, so that, when the steel sheet pile wall is removed, the steel sheet piles can be pulled out without damaging a base structure.

REFERENCE NUMERALS

-   100: Steel sheet pile -   101: Web portion -   102: Flange portion -   103: Joint portion -   104: Crosspiece -   105: Fixing runner -   201, 202: Formwork panel -   203: Screw -   204: Runner -   205: Cap -   300: Support 

1. A retaining wall constructed by preliminarily driving steel sheet piles sequentially to construct a steel sheet pile wall forming continuous corrugation and performing excavation on one side of the steel sheet pile wall, the retaining wall comprising: a first formwork panel arranged parallel to the steel sheet pile wall in a direction parallel to and in close contact with the one side of the steel sheet pile wall; and a second formwork panel arranged parallel to the steel sheet pile wall at a position corresponding to the width of a base structure to be constructed.
 2. The retaining wall according to claim 1, wherein the formwork panel is fixed to the closely-contacting steel sheet piles by a fixing member.
 3. A construction method for a retaining wall, comprising: a step of preliminarily driving steel sheet piles sequentially to construct a continuously-corrugated steel sheet pile wall in a plot of land where the retaining wall is constructed; a step of performing excavation on one side of the steel sheet pile wall; a step of arranging a first formwork panel parallel to the steel sheet pile wall in close contact with the one side of the steel sheet pile wall; a step of arranging a second formwork parallel to the steel sheet pile wall at a position corresponding to the width of a base structure to be constructed; a step of casting concrete to construct the base structure; a step of performing backfill by feeding soil into recessed portions of the steel sheet pile wall; and a step of pulling out the steel sheet pile wall. 